The overall objectives of this project are to characterize the type-specific and interspecific antigens of erythrocytes, serum, isozymes, and other tissues--especially reproductive tissues--in rhesus monkeys. These immunogenetic markers are then studied for their intrinsic interest as well as for their possible roles in reproduction and development. Specifically, we have produced and characterized over 25 monospecific blood typing reagents which detect blood groups in more than 12 genetically independent blood group systems. These markers have been very useful in solving cases of disputed parentage and for identification. We have found that all of the conditions that cause hemolytic disease in newborn humans appear to exist in the rhesus monkey, yet the newborn rhesus somehow is protected from the disease. Our evidence suggests that the passively acquired maternal antibodies coat the newborn's erythrocytes and protect it from phagocytosis. We have confirmed the mode of inheritance of the 6-phosphogluconate dehydrogenase (6PGD) and phosphohexase isomerase (PHI) isozymes and we have clearly elucidated 11 different transferrin alleles. Finally, we have found that all rhesus possess the human Duffy "b" antigen which in humans appears to be a receptor for the parasite that causes malaria.